One of the most frequent comorbidities of fibromyalgia is major depression. Agomelatine is a new antidepressant whose mechanims of action include both agonism at melatonin receptores and 5-HT2C blocking properties which, in addition to antidepressant efficacy, has shown sleep-improving properties. As unrefreshed sleep is a common symptom in fibromyalgia we hypothetized that agomelatine treatment of patients with concomitant depression and fibromyalgia could improve both depressive symtomatology and sleep quality. Thus, the objectives of the present study are the following: